Incomplete Display on Screen 
The Miditzer requires a screen resolution of at least 1024x768. If you don't see the entire Miditzer main screen, right click on your desktop and select Properties. Select the settings tab. You may be able to increase the resolution here. If not, you will need to upgrade your hardware to see the entire Miditzer main screen.

No Sound
If you don't hear a sound, start with the obvious.  Do you have speakers connected?  Are they turned on?  Is the volumne high enough?  Try another application that sends sound to the the speakers, preferably something that plays a MIDI file. 
Try this MIDI file:  Play
If you can hear a MIDI file being played then you probably need to adjust the Miditzer to use a different MIDI Output device.  Click on the yelow "M" in the upper left corner of the screen to open the Miditzer's menu and select the "Miditzer Settings..."
The Miditzer Settings dialog will open.
 
Don't Worry.  You won't need to deal with most of the things on this screen for now.